Sensitivity of electronic structure to crystal distortions in infinite-layered LaNiO2

Recent observations of unconventional superconductivity (SC) in thin films of LaNiO₂ (critical temperature T_c≃ 10 K) and in bulk single crystals of La₃⁢Ni₂⁢O₇ under pressure T_c ≃ 80K have cemented a long sought-after class of SC nickelates. In La_1–x⁢Sr⁢_x⁢NiO₂, SC appears only in films for reasons not understood. We perform a combination of experiments to probe the crystal structure and magnetic order in bulk LaNiO₂ together with ab initio calculations of the electronic structure. We find that the infinite layers are naturally buckled out-of-plane. The electronic bands are largely unaffected by the buckling, but uniaxial compression along the c axis may lead to a Lifshitz transition.